Recently we have moved a few months production data to a new schema in Test environment.
Some of the data were masked to maintain privacy(Say for a particular column Credit card # of datatype varchar2(16), the number was masked like this: 'qryopnegfrnlukji'.In the new schema, we are facing some performance issues like the query which was previously taking 1 or 2 sec is now taking 2/3 minute or at times more than that. We tried for a small date range.

To my understanding, One of the factor is memory space. And What are the other factors that I should look into it? Your suggesions will help a lot.